The German Reinheitsgebot (Beer Purity Law) is not the oldest food law in the world. There are laws going back more than 3000 years before the Reinheitsgebot that concern food. The Law was introduced as a Landesverordnung (State Act) in Bavaria, and only in 1918 it was called Reinheitsgebot for the first time.

Mostly, this law in Bavaria is used to refer to the Reinheitsgebot, and so will I hereinafter. The Law prescribes that the only ingredients allowed in beer are water, malted barley, and hops. Yeast only became known as an ingredient in the 19th century, as its role in fermentation only became known then. The Reinheitsgebot was introduced for the first time in 1487. In 1516 it was adopted in other parts of Bavaria.

Why are such laws needed? There are several reasons to introduce such laws, and one of the reasons of a law that preceded the Reinheitsgebot was a famine. Other grains were needed for other foods, and thus that law only prescribed barley as the allowed ingredient. For the Reinheitsgebot, one of the reasons lies in the preservation of the drink. At the time, brewers used all kinds of ingredients to preserve the beer, many of which were not all that healthy. Hops was the way to go, and thus it was introduced as the only allowed ingredient for preserving beer. Another reason was to prevent shortages of wheat and rye, which were reserved only for bakers. This way, bread could stay affordable.

It expanded to other parts of Germany in 1906 after the German unification in 1871, when Bavaria insisted on introduction of the Law all over the country. This could prevent competition from other kinds of beers, for example popular northern German cherry beer and other special beers. The Reinheitsgebot was later included in the Biersteuergesetz (Beer Taxation Law). A dispute arose in the 1950s, when the so-called Süßbier (sweet bier) was allowed in Germany, but in Bavaria. This contained a certain amount of sugar too. That was not allowed in Bavaria, and this ultimately caused upheaval in the State. The brewers negotiated with the Bavarian government that there should be a ban on imports of Süßbier. They got what they wanted. In the rest of Germany, it was legal to add sugars. However, in the 1960s, Germany as a whole fought to prevent imports from other Member States of the European Economic Community (EEC). The EEC wanted to harmonize the production Laws for beer. The European Court of Justice ruled in 1987 that beers imported into Germany could not be subjected to the Reinheitsgebot, because it was seen as a hindrance of the free internal market. However, the laws were still applicable for German beers.

Today, there are still strict laws for the production of bottom-fermented beers, which are regulated in the 2005 Bierverordnung (Beer Act). Many brewers still claim to follow the Reinheitsgebot. Some because they have to, others because it makes great marketing. Some even claim to follow it, but use wheat instead of barley.